1. Field of the Invention
The present invention relates to a thin electronic apparatus which uses a plate member to enhance the rigidity of the apparatus as well as to serve a multipurpose application.
2. Related Background Art
Recently, apparatuses such as electronic calculators and electronic translators have been remarkably miniaturized and lightened. Card type apparatuses have become common.
The miniaturized and lightened apparatuses can be used under a wide variety of circumstances because of their excellent portability. The apparatuses must be sealed from their environments concerning temperature and/or humidity and must have measures against static discharge.
For example, there is a problem in that the circuit elements, such as metal oxide semiconductors used for energy reservation, are prone to be influenced by static charges, i.e., they are prone be damaged by discharge of static charges stored in the operator's body or clothes via the keyboard during operation, or stored data may be changed where of a memory is affected. Thus metal parts which are prone to bear static charge should be connected to the circuit ground potential.
Such a grounded member must be easily mounted in the miniaturized apparatus without enlarging the entire apparatus and ensure secured connection to ground potential against bending, twisting and/or shock (first problem).
The entire circuit is adapted to be driven by solar cells for power reservation. However, especially, a thin apparatus such as a card-like apparatus or an electronic calculator is often put into a commutation-ticket holder when carried and thus it is subjected to stress such as warping, torsion or bending. Generally, a thinned apparatus has no structure to have its circuit substrate accommodated in a case, but a laminated structure of a substrate, an indicator and solar cells through reinforcing plates.
Thus, there is a problem in that the directly held and laminated indicator and solar cells can be damaged by stresses such as bending and/or torsion. As a low power consumption indicator, there is a liquid crystal indicator which has a structure to seal a liquid crystal between thin glass plates. A solar cell includes one which employs a thin plate of a single crystal of silicon or one which employs an amorphous silicon layer formed on a glass plate. These indicator and solar cells often have a thin glass substrate for purposes of thinning and are very fragile so as to be damaged with a slight stress (second problem).
Conventionally, it is known that some apparatuses have a structure in which the case or frame pressably supports many key-top members constituting part of the keyboard. Thus when a key-top member is pressed and displaced to move movable contacts of conductive rubber underlying the key-top member into contact with a printed circuit board, the keying-in of data or commands is performed.
In order to fabricate such apparatus, troublesome work is required which includes appropriate insertion and positioning of many individually molded key-top members with individual different key symbols in the corresponding openings in the frame or case. Furthermore, during the work, an accident is prone to occur which includes tumbling the frame and case to scatter the key-top members.
Since a key-top member slides up and down relative to its corresponding opening, the clearance between the key-top member and its corresponding opening must be controlled with high accuracy and considerable time is required for machining molds for many key-top members.
Furthermore, since the movable contacts are operated by the corresponding key-top member and a separate conductive rubber member, the spacings between the movable contacts and the corresponding fixed contacts on the circuit substrate are not fixed and the operation strokes of the keys are not constant when data or commands are keyed in (third problem).